The travelling speed of cranes varies from_________________?
(A) 20 to 30 m/s
(B) 10 to 15 m/s
(C) 5 to 10 m/s
(D) 1 to 2.5 m/s
The cost of an induction motor will increase as________________?
(A) horsepower rating increases but r.p.m. decreases
(B) horsepower rating decreases but r.p.m. increases
(C) horsepower rating and operating speed increases
(D) horsepower rating and operating speed decreases
While selecting motor for an air conditioner which of the following characteristics is of great importance ?
(A) Type of bearings
(B) Type of enclosure
(C) Noise
(D) Arrangement for power transmis¬sion
(D) None of the above
Which of the following alternatives will be cheaper ?
(A) A 100 H.P. AC. three phase motor
(B) Four motors of 25 H.P. each
(C) Five motors of 20 H.P. each
(D) Ten motors of 10 H.P. each
Which of the following motors has series characteristics ?
(A) Shaded pole motor
(B) Repulsion motor
(C) Capacitor start motor
(D) None of the above
For a D.C. shunt motor which of the following is incorrect ?
(A) Unsuitable for heavy duty starting
(B) Torque varies as armature current
(C) Torque-armature current is a straight line
(D) Torque is zero for zero armature current
Addition of trivalent impurity to a semiconductor creates many_______________?
(A) Holes
(B) Free electrons
(C) Valence electrons
(D) Bound electrons
As the doping to a pure semiconductor increases, the bulk resistance of the semiconductor_______________?
(A) Remains the same
(B) Increases
(C) Decreases
(D) None of the above
A hole in a semiconductor is defined as_________________?
(A) A free electron
(B) The incomplete part of an electron pair bond
(C) A free proton
(D) A free neutron